The present disclosure relates to display devices having a sub-pixel structure in which each pixel includes four color sub-pixels that are, for example, a red (R) sub-pixel, a green (G) sub-pixel, a blue (B) sub-pixel, and a white (W) sub-pixel, and to electronics apparatuses equipped with such display devices.
One of the most typical methods for displaying color images used in a display device equipped with plural pixels is a method in which three sub-pixels that correspond to three primary colors, that is, R (red), G (green), and B (blue) one-by-one are disposed in each pixel, and the luminance level of each sub-pixel is individually adjusted.
With the use of this method, it is possible to arbitrary set the chromaticity point and luminance level of an entirety of a pixel, and a color image can be displayed.
An example of a display device capable of displaying color images using such a method is a liquid crystal display device. This type of liquid crystal display device typically includes a backlight device that emits a white light and a liquid crystal panel having R, G, and B color filters that are respectively provided for an R sub-pixel, a G sub-pixel, and a B sub-pixel. In addition, usually polarization plates are disposed at the entrance side and exit side of this type of liquid crystal panel. Therefore, the intensity of emitted light from the backlight device is typically decreased owing to the polarization plates and the color filters, and the light utilization factor through the entirety of the liquid crystal device becomes less than ten percent. As a result, a large amount of energy is needlessly lost in the liquid crystal display device, which leads to an increase in electricity consumption.
In order to reduce the electricity consumption when a liquid crystal display device is displaying images, a liquid crystal panel equipped with pixels each of which includes four color sub-pixels has been proposed (For example, refer to Japanese Examined Patent Application Publication No. 4-54207). Concretely speaking, these four color sub-pixels are three R, G, and B color sub-pixels, and one Z color sub-pixel (for example, a white (W) or yellow (Y) sub-pixel) whose luminance is higher than the luminances of the above three sub-pixels. Luminance efficiency can be further increased and electricity consumption can be further lowered in the case where images are displayed using image signals corresponding to such four color sub-pixels compared with the case where images are displayed by supplying image signals corresponding to the three R, G, and B colors to each pixel having an existing sub-pixel structure composed of R, G, and B sub-pixels.
In addition to the above-described liquid crystal display device, an example of a display device having a sub-pixel structure in which each pixel includes R, G, B, and Z color sub-pixels is an organic EL (electroluminescence) display device with a self-emitting function (Refer to Japanese Patent No. 4434935, for example). In addition, a method (a method of color conversion processing (RGB/RGBZ conversion processing)), in which output image signals corresponding to four colors R, G, B, and Z are generated on the basis of input image signals corresponding to three R, G, and B colors, is proposed, for example, in Japanese Unexamined Patent Application Publication No. 2008-107507, Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2009-500654, and Japanese Patent No. 4494808.